Antiknock liquid hydrocarbon fuel containing organic nitrogen containing compounds

ABSTRACT

LIQUID HYDROCARBON FUELS ARE PROVIDED WHOSE ANTIKNOCK PROPERTIES ARE IMPROVED BY ADDING THERETO A SMALL AMOUNT OF AN AMINOFULVENE.

Int. Cl. C101 1/22 US. Cl. 44-63 13 Claims ABSTRACT OF THE DISCLOSURELiquid hydrocarbon fuels are provided whose antiknock properties areimproved by adding thereto a small amount of an aminofulvene.

BACKGROUND OF THE INVENTION Field of the invention This inventiongenerally relates to improved fuels for internal combustion engines.More particularly, it relates to improving the antiknock properties ofsuch fuels by adding thereto a metal-free additive capable of impartingsuch properties.

Discussion of the prior art The octane number of a fuel is a measure ofthe ability to resist detonation caused by auto-ignition. Whendetonation occurs, it results in a rapid rise in combustion chamberpressure above that for normal combustion and causes high frequencypressure fluctuations and an audible sound that is referred to as knock.When detonation (knock) occurs, heat is released which promotes furtherdetonation, causes a loss of power and, if sustained, can result inengine damage. Antiknock requirements of spark ignition engines increasewith increasing compression ratio and are affected by such things ascarburation, spark timing, type of transmission and other engine/vehicledesign characteristics and changes in ambient conditions such astemperature, humidity and absolute pressure.

Specifically, it is well known that knock in spark-fired engines is dueto the relatively slow oxidation of the endgas prior to the arrival ofthe flame front, the immediate cause being the extremely rapidcombustion of the last part of the charge to burn.

It has been determined that the most economical burning of the fuel isobtained at the higher compression ratios, and as has already beenstated, such higher compression ratios require higher octane numbers forknockfree operation. Because the design of modern automobile engines hasbeen toward increased compression ratios, the demand has been for fuelsof constantly improved antiknock quality. Refiners have met this demandby new and improved refining techniques and by the use of antiknockadditives.

Antiknock agents most widely in use are those of the so-called metallictype, the leading example of which is tetraethyl lead. It has long beenknown, however, that the use of this and other metal-containingantiknock agents contributes to other difiiculties associated with theoperation of high compression engines, as for example, spark plugfouling and preignition. Leaded gasolines have also recently beencriticized for their alleged role in polluting United States Patent 63,706,541 Patented Dec. 19, 1972 the atmosphere. The art has for sometime now been searching for non-metallic antiknock agents, and thepresent campaign to reduce or eliminate leaded agents has added newimpetus to the search.

The most widely known non-metallic antiknock agents are aniline andcertain alkyl derivatives thereof. This class of materials isrepresented by the formula where R, R and R are hydrogen or lower alkyl.Probably the best known non-metallic agent defined by this formula isN-methylaniline.

In the series Where R and R" are hydrogen and R' is alkyl, a decrease inantiknock effectiveness with increasing alkyl chain length occurs. Thisis illustrated in the following table.

Research octane Fuel blend: number (F--1) Base fuel 2 60.0 Base+3%aniline 75.4 Base+3% N-methylaniline 78.0 Base+3% N-ethylaniline 71.7Base+3% N,Ndimethylaniline 60.0

1 ASTM designation D908-53, ASTM Manual of Engine Test Methods forRating Fuels, 1953 Supplement.

AS'IM primary reference fuel (60% iso-octane, 40% nheptane).

Other compounds which are known to beefiective as antiknock agents arethe phenylenediamines, represented by the formula where R, R, R" and R'"may be hydrogen, lower alkyl or aryl. Also, some of the nitriles, suchas .propionitrile and isocyanates such as phenylisocyanate have someslight elfect on antiknock properties of a fuel. These latter twoclasses are, therefore, the least important of those mentioned.

US. Pat. 2,881,061 discloses as antiknock agents, a group of compoundsin which the N-alkyl group is made to form a ring attached to a benzenering ortho to the amine function. Such compounds have the generalformula where n may be zero or 1.

SUMMARY OF THE INVENTION In accordance with the invention, there isprovided a liquid hydrocarbon fuel composition comprising liquidhydrocarbon fuel and an amount sufficient to impart antiknock propertiesthereto of a compound of the formula wherein X is carbon or nitrogen, Ris hydrogen or hydrocarbyl, R is selected from the group consisting ofRIII \RIIII wherein R'" and R"" are selected from the group consistingof hydrogen, hydrocarbyl, and C -C alkyl-substituted hydrocarbyl;

--R and HN R \J V wherein the ring portions contain from about 3 toabout 6 methylene groups, and may contain another heteroatom such asoxygen or nitrogen, R" is a hydrocarbyl, an R CHO group or a condensed--R OHO group, R being a hydrocarbyl, R is a hydrocarbyl and y is zeroor 1, y being zero when X is nitrogen.

In the above hydrocarbyl shall means an alkyl or cycloalkyl containingfrom 1 to about 12 carbon atoms and an aryl or an aralkyl groupcontaining from 6 to about 20 carbon atoms. Condensed --R CHO groupshall mean such group condensed with a glycol such as ethylene glycol,hexamethylene glycol and the like, or with a primary amine such as analkyl amine containing from 1 to about 16 carbon atoms, aniline,substituted aniline and the like, or with mixtures of such glycols andamines.

Preferred in the practice of this invention are those materials whereinR is selected from the group consisting of hydrogen and alkyl of from 1to about 6 carbon atoms, R is selected from the group consisting of RV lT and N H wherein R' and R"" are selected from the group consisting ofhydrogen, alkyl of from 1 to about 8 carbon atoms and aryl of from 6 toabout 14 carbon atoms, i.e. phenyl, naphthyl and anthracyl, R is alkylof from 1 to about 6 carbon atoms, and R" is selected from the groupconsisting of hydrogen, alkyl of from 1 to about 6 carbon atoms, CH anda condensed CHO.

Compounds active as antiknock agents for hydrocarbon fuels and whichcome within the above formula include: dimethylarninofulvene;diethylaminofulvene; dibutylaminofulvene; dioctylaminofulvene;ethylmethyl-aminofulvene; methyl-octyl-aminofulvene;methyl-phenyl-aminofulvene; methyl-, ethyl-, butyl-, octyl-, phenyl-,tolyl-, xylyland cresylaminofulvene; cyclopentyl-, cyclohexyl-, andcyclooctylaminofulvene; those 6-fulvenes wherein N is a part of a ringsystem, such as those made from pyrrole, morpholine and piperazine.Compounds with the above substituents, but where X is nitrogen areuseful also, as for example a compound of the formula DESCRIPTION OFSPECIFIC EMBODIMENTS The agents described herein represent a new classof fuel antiknock additives. As is apparent from the formulae set forthabove, all members contain at least one nitrogen atom somewhere in themolecule. This nitrogen may be attached to the external carbon ornitrogen atom of the ring, or it may be separated therefrom by anothermember. There is some evidence tending to establish the necessity forsuch nitrogen atom. For example, when X in the general formula is carbonand R and R are methyl groups, such compound is ineffective as anantiknock agent.

It is also believed that the effectiveness of the compound is influencedby structural factors other than the presence of a nitrogen or of amember double bonded to the cyclopentadiene ring. Thus, a compound ofthe for- CHaOOG CO 0 CH3 which has the H-fi-N-N moiety, has no effectwhatever on the octane number of a fuel.

It is not known how or why the additive functions as an antiknock agent.While it is not known whether it is the compound per se or its oxidizedform which is the effective agent, we believe that the oxidized form isan effective agent. It is known, for example, that the compounds of theinvention react readily with oxygen in almost a mole to mole ratio. Verylikely, then, the fulvene or fulvene-type derivative, reacted with onemole per mole of oxygen, is an active component.

That the oxidation product is an effective component is bolstered by thefact that the activity is increased and sustained by adding certainmaterials known to solubilize such oxidation products. One usefulsolubilizer" is aniline. Others which may be effective for this purposeare n methylaniline, N,N dimethylaniline, N,N-dimethylacetamide andfatty acid esters, such as t-butyl acetate and methyl and ethylvalerate.

Methods for preparing the compounds of this invention are known. Ingeneral, they may be prepared by reacting the appropriate methyl sulfateor fluoroborate complex with sodium cyclopentadienylsodium. For example,Organic Synthesis, vol. 47, pp. 52-53 discloses a method for preparingthe complex Hi0 HCHzOSOr EXAMPLE 1 Preparation of H-CN(CH:)2

(a) One mole of dimethylformamide and 1 mole of dimethyl sulfate weremixed and allowed to stand at room temperature for 24 hours. One mole ofthe complex was obtained as a viscous colorless oil.

(b) To a solution of 0.5 mole of cyclopentadienylsodium (prepared insitu from cyclopentadiene and sodium hydroxide) in 250 ml. oftetrahydrofuran was added 0.5

mole of the complex made in .(a) above. After stirring for 2 hours at 20C., filtration and evaporation of the solvent and recrystallization fromcyclohexane gave a 50% yield of dimethylaminofulvene, the product havinga melting point of 67-68 C.

EXAMPLE 2 Preparation of (a) The complex was prepared in the mannerdescribed for the Example 1 complex from one mole each ofdimethylacetamide and dimethyl sulfate.

(b) To 0.5 mole of the complex made in part (a) was added 0.5 mole ofcyclopentadienylsodium and the reac tion was carried out as shown inpart (b) of Example 1.

In the examples which follow, unless so stated, the procedures,including quantities of reactants, were similar to those described inExample 1.

EXAMPLE 3 Preparation of H-C-N CH3) 1 II Ite The complex of Example 1(a)was reacted with methylcyclopentadienylsodium substantially as describedin Example 1(b) EXAMPLE 4 Preparation of HCN Using procedures alreadydescribed, a complex of the formula OCH;

was prepared from the complex of Example 1(a) and pyrrolidine, and thisin turn was reacted with cyclopentadienylsodium to give the product,melting point 105.5-107" C.

EXAMPLE 5 Preparation of The compound was prepared by reacting equimolaramounts of pyrrole 2-carboxaldehyde and cyclopentadiene in methanol, inthe presence of a small amount of npropylamine. The product was obtainedas copper colored crystals and had a melting point of 120121 C.

EXAMPLE 6 Preparation of The complex omofi-monawmosor was prepared byreacting equimolar amounts of N-nitrosodimethylamine and dimethylsulfate. Reaction of this complex with cyclopentadienylsodium gave theproduct, an orange-colored oil boiling at -101" C. at 8 mm. of Hg.

was prepared from n-methylformanilide and triethyloxonium fluoroborate.Reaction of this complex with cyclopentadienylsodium gave the product,melting at 67.5- '68.5 C.

EXAMPLE 8 Preparation of The compound of Example 1 was heated in anexcess of aniline for 8 hours at 60 C.

EXAMPLE 9 Preparation of The compound of Example 1 was heated in anexcess of dodecylamine for 8 hours at 60 C.

In a similar manner, the compound I OHC CHO was prepared.

EVALUATION OF PRODUCTS Fuel blends of the compounds described in theabove examples were prepared and the Research Octane Numbers (RON)thereof were determined. The RON (ASTM D-2699), while determined undermold test engine operation, is a reliable tool for predictingperformance of the fuel in actual use. The following table shows theresults obtained.

TABLE 1 Research Weight octane percent number Test number Compound addedcompound (RON) 1 1. 0 93. 6 l 1. 0 93.0 (a) i 0. 5 85. 7 (b) 0. 5 91. 8

8 Example 6 I 0.5 85. 1 9 Example 7.. O. 5 92. 2 10-.-" Example 8.- 10.5 91. 5 11 Example 9 l 0. 5 92. 4

12 HCN(CH;) 1 0. 04 92. 8

CH0 i i CHO See footnotes at end of Table 2.

The compounds of this invention seem to have an additional uniquecharacteristic. When they are added to a clean base fuel and this fuelis used in an engine for a time, there is a pm-conditioning" efiFectobserved when the CFR engine is run under normal condition, that is tosay, if the supply of base fuel plus additive is removed and a clearbase fuel substituted, the RON will remain at the level reached prior tosubstitution, and in some instances will even exceed such RON. In oneoperation involving the compound of Test 3 in the above table, the fuelplus additive was run for about 68 minutes, at which time this supplywas shut off. A clear base fuel was used to run the engine, and it wasfound that the RON so found was at a higher level from about 77 minutesto about 96 minutes (these times are totals of both runs). The followingsummarizes the data obtained.

TABLE 2 Cumulative RON, Fuel minutes average B 0 91. 2 Base plus 0.5%additive.-.. 4 9e 1 D0. 68 99. 1

Engine shutdown and clear base fuel substituted:

The fuel used, unless indicated otherwise, in obtaining the datasummarized in Tables 1 and 2 had the following characteristics: 10%boiled to 122 F., 50% to 223 F. and 90% to 345 F., with an end point01403" E; 33% aromatics, 9.4 olefins and 57.6% saturates. It wascomposed of 40% 100 reformate, 30% heavy T00, 10% light T00, 10% 100straight run, 6% light alkylate and 4% butane.

9 Referring to Table 1, the fuel used was a synthetic" fuel containing23.6% aromatics, 10.3% olefins and 66.1% saturates. It had an RON of .2.Contained also 0.5% by weight of aniline.

percent of compound RON 1 Actual automobile test.

It will be understood that the additives of the invention may beadvantageously utilized in any hydrocarbon fuel 8 suitable for use incombustion engines, whether automotive or aviation.

The antiknock action of the compounds of the present invention isindependent of other antiknock agents of either the metallic ornon-metallic type. Hence they will increase the anti'knock ratings offuels even though other antiknock agents are present. Furthermore, otheradditives designed to impart various improved properties to the fuel maybe used along with the present additives. Thus, antioxidants, metaldeactivators, anti-rust, antistalling and ignition control compounds maybe used.

The amount of additive which may be used in the fuel will depend uponthe particular fuel and the degree of improvement desired. In general,from about 0.1% to about 5% by Weight of additive may be used.Preferably, we use from about 0.1% to about 2% by weight.

Although the present invention has been described with certain specificembodiments, it is to be understood that modifications and variationsmay be resorted to without departing from the spirit and scope of thisinvention as those skilled in the art will readily understand. Suchmodifications and variations are considered to be within the purview andscope of the appended claims.

We claim:

1. A liquid hydrocarbon fuel composition comprising a liquid hydrocarbonfuel for a spark ignition engine and an amount sufficient to impartantiknock properties thereto of a compound of the formula wherein X isselected from the group consisting of nitrogen and carbon, R is selectedfrom the group consisting of hydrogen and alkyl of from 1 to about 6carbon atoms, R" is selected from the group consisting of hydrogen,alkyl of from 1 to about 6 carbon atoms, -CH0 and condensed --CHO, R isselected from the group consistwherein R' and R"" are selected from thegroup consisting of hydrogen, alkyl of from 1 to about 8 carbon atoms,and aryl of from 6 to about 14 carbon atoms, R is alkyl of from 1 toabout 6 carbon atoms, and y is zero or 1, y being zero when X isnitrogen.

2. The composition of claim 1 wherein said compound is present in anamount of from about 0.1 to about 5% by weight.

3. The composition of claim 1 containing from about 0.1 to about 5% byweight of a compound of the formula 4. The composition of claim 1containing from about 0.1 to about 5% by weight of a compound of theformula 5. The composition of claim 1 containing from about 0.1 to about5% by weight of a compound of the formula II l 6. The composition ofclaim 1 containing from about 0.1 to about 5% by weight of a compound ofthe formula 7. The composition of claim 1 containing from about 0.1 toabout 5% by weight of a compound of the formula I I HAN 8. Thecomposition of claim 1 containing from about 0.1 to about 5% by weightof a compound of the formula 9. The composition of claim 1 containingfrom about 0.1 to about 5% by weight of a compound of the formula H-C-N10. The composition of claim 1 containing from about 0.1 to about 5% byweight of a compound of the for mula C Ha 10 11. The composition ofclaim 1 containing from about 0.1 to about 5% by weight of a compound ofthe formula 12. The composition of claim 1 containing from about 0.1 toabout 5% by weight of a compound of the formula l ono lono 13. A methodof pre-conditioning an internal combustion engine comprising the step ofrunning said engine with a liquid hydrocarbon fuel compositioncomprising a liquid hydrocarbon fuel and an antiknock amount of acompound of the formula wherein X is selected from the group consistingof nitrogen and carbon, R is hydrogen and alkyl of from 1 to about 6carbon atoms, R" is selected from the group consisting of hydrogen,alkyl of from 1 to about 6 carbon atoms, CH0 and condensed -CHO, R isselected from the group consisting of R!!! -N i j and \RIIII N HReferences Cited UNITED STATES PATENTS 1,786,860 12/1930 Midgley, Jr. eta1. 4474 3,402,201 9/1968 Schmerling 4474 DANIEL E. WYMAN, PrimaryExaminer Y. H. SMITH, Assistant Examiner US. Cl. X.R.

